Research lectures, seminars and events
The events listed in this area are research seminars, workshops and lectures hosted by Durham University departments and research institutes. If you are not a member of the University, but wish to enquire about attending one of the events please contact the organiser or host department.
|November 2017||January 2018|
Events for 15 December 2017
'Hell, Heaven and Hope. A journey through life and the afterlife with Dante', Exhibition curated by Dr Annalisa Cipollone
Contact firstname.lastname@example.org for more information about this event.
Florian Niedermann: Extra dimensional self-tuning of the vacuum energy: obstructions and ways around
Gravitational models of self-tuning are those in which vacuum energy has no observable effect on spacetime curvature even though it is a priori unsuppressed below the cut-off, thereby avoiding the cosmological constant problem. We study a class of six dimensional braneworld models that implement self-tuning by decoupling vacuum energy from the gravitational sector induced on the brane. Special care is taken to come up with a consistent core model that resolves the brane as cylindrical vorton carrying charge and current. By studying the setup in a thin-wall approximation for vanishing charge, we find that phenomenological constraints push the theory into a pathological parameter regime. In the second part, we will propose a model independent analysis of self-tuning based on a spectral decomposition of the exchange amplitude for conserved sources of energy-momentum. This provides us with a deeper understanding of the failure of the extra dimensional model and allows us to identify new obstructions to self-tuning, complementing a famous no-go theorem by Weinberg. Finally, we search for novel ways around our obstructions and highlight different interesting possibilities.
Solar flares are highly explosive events which release significant quantities of energy (up to 10^32 ergs) from specific magnetic configurations in the solar atmosphere. As part of this process, flares produce unique signatures across the entire electromagnetic spectrum, from radio to ultra-violet (UV) and X-ray wavelengths, over extremely short length and timescales. Many of the observed signals are indicative of strong particle acceleration, where highly energised electron and proton populations rapidly achieve MeV/GeV energies and therefore form a significant fraction of the energy budget of each event. It is almost universally accepted that magnetic reconnection plays a fundamental role (on some level) in the acceleration of particles to such incredible energies.
In this talk, I will briefly summarise a series of recent experiments where test particles are introduced into a number of 3D magnetic reconnection configurations. I will discuss the particle population response to each configuration and what these responses might infer for both simulations and observations of magnetic reconnection in the flaring solar corona.
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